Note (probably harmless): No library found for '-lfftw3' is not a known MakeMaker parameter name. Writing Makefile for Math::FFTW cp lib/Math/FFTW.pm blib\lib\Math\FFTW.pm D:\cpanrun\build\5-6-1\bin\perl.exe -Id:\cpanrun\build\5-6-1\lib -Id:\cpanrun\build\5-6Please specify prototyping behavior for FFTW.xs (see perlxs manual) NMAKE : fatal error U1077: 'cl' : return code '0x2' Stop. cpanrun\build\5-6-1\bin\perl.exe -Id:\cpanrun\build\5-6-1\lib -Id:\cpanrun\build\5-6-1\lib -MExtUtils::Command -e mv FFTW.xsc FFTW.c cl -c -I. -nologo -O1 -MD -Zi -DNDEBUG -DWIN32 -D_CONSOLE -DNO_STRICT -DHAVE_DES_FCRYPT -DPERL_IMPLICIT_CONTEXT -DPERL_IMPLICIT_SYS -DPERL_MSVCRT_READFIX -O1 -MD -Zi -DNDEBUG -DVERSION=\"0.01\" -DXS_VERSION=\"0.01\" -ID:\cpanrun\build\5-6-1\lib\CORE FFTW.c FFTW.c FFTW.xs(4) : fatal error C1083: Cannot open include file: 'fftw3.h': No such file or directory